Liquid hydrocarbons are widely used in open flame and internal combustion devices such as oil fired burners and internal combustion engines. One of the common problems associated with such combustion devices is the emission of NO.sub.x. Many attempts have been made in the past to reduce NO.sub.x emissions but these normally have resulted in reduction of combustion efficiency.
Oil fired furnaces and boiler arrangements are used world-wide in producing heat and electricity. Normally, petroleum distillates such as fuel oils are used in such oil fired burners. It is highly unusual to burn directly mined crude oil because of the considerable increase in pollutants in the combustion of the products, particularly soot emissions.
It has been appreciated for some time that additives may be included in organic materials which are used in oil fired furnaces and the like. A particularly suitable additive is ferrocene which is one of many of dicyclopentadienyl iron compounds. Examples of these additive constituents are disclosed in U.S. Pat. No. 3,535,356. This patent mentions that ferrocene and its derivatives are valuable additives in various organic compositions particularly hydrocarbons comprising gasolines and other petroleum products including lubricating oils, turbine oils, transformer oils, kerosines, diesel fuels, jet fuels, fuel oils, greases, asphalts, waxes, insecticides and the like. It is not mentioned, however, in this reference what, if any, effect ferrocene may have on the combustion of these products. However, in U.S. Pat. No. 3,122,577 mention is made that ferrocene is suitable as an antiknock agent in gasoline compositions.
U.S. Pat. No. 3,341,311 discloses the use of ferrocene in liquid hydrocarbon fuel oils. The purpose of the ferrocene is to improve the ignition and combustion characteristics of the fuel. The use of such ferrocene in fuel oils as per the examples, reduces the presence of carbon in the combustion gases, and decreases the amount of deposits in the combustion apparatus.
None of these references, however, contemplate the use of ferrocene and its derivatives in liquid hydrocarbons to achieve improvement in the combustion efficiency and reduction in NO.sub.x emissions.